Re: [PATCH 5/5] powerpc/8xx: fix possible object reference leak

From: Christophe Leroy
Date: Fri Mar 22 2019 - 03:10:01 EST

On 03/22/2019 03:05 AM, Wen Yang wrote:
The call to of_find_compatible_node returns a node pointer with refcount
incremented thus it must be explicitly decremented after the last
irq_domain_add_linear also calls of_node_get to increase refcount,
so irq_domain will not be affected when it is released.

Should you have a:

Fixes: a8db8cf0d894 ("irq_domain: Replace irq_alloc_host() with revmap-specific initializers")

If not, it means your change is in contradiction with commit b1725c9319aa ("[POWERPC] arch/powerpc/sysdev: Add missing of_node_put")

Detected by coccinelle with the following warnings:
./arch/powerpc/platforms/8xx/pic.c:158:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 136, but without a corresponding object release within this function.

Signed-off-by: Wen Yang <wen.yang99@xxxxxxxxxx>
Cc: Vitaly Bordug <vitb@xxxxxxxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
arch/powerpc/platforms/8xx/pic.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/platforms/8xx/pic.c b/arch/powerpc/platforms/8xx/pic.c
index 8d5a25d..13d880b 100644
--- a/arch/powerpc/platforms/8xx/pic.c
+++ b/arch/powerpc/platforms/8xx/pic.c
@@ -155,6 +155,7 @@ int mpc8xx_pic_init(void)
ret = -ENOMEM;
goto out;
+ of_node_put(np);
return 0;

I guess it would be better as follows:

--- a/arch/powerpc/platforms/8xx/pic.c
+++ b/arch/powerpc/platforms/8xx/pic.c
@@ -153,9 +153,7 @@ int mpc8xx_pic_init(void)
if (mpc8xx_pic_host == NULL) {
printk(KERN_ERR "MPC8xx PIC: failed to allocate irq host!\n");
ret = -ENOMEM;
- goto out;
- return 0;